20 November 2018

Recent Changes in United States Heat Wave Characteristics Derived From Multiple Reanalyses


Near-surface temperature and specific humidity from PRISM & 4 reanalyses are used to quantify historical trends in frequency (freq), intensity (int.) & spatial extent (area) of extreme T-only & T & TE extreme heat days (EHD). The southwest and southern Great Plains exhibit strong positive trends in freq./int./area T-only EHD. All other regions exhibit strongest positive trends in freq/int./area T&TE EHD. 


Impacts from extreme heat (T)  depend on specific humidity (Q). Dry heat (high T only) leads to agricultural losses. Wet heat (high T & high TE) leads to excess human mortality & morbidity. Thus, we need to use composite variables (e.g. equivalent temperature that combines T & Q) to characterize heat waves. TE is also an integrative metric of static energy & at the energy-water-land nexus, it depends on sensible v. latent heat fluxes).


Our research illustrates long-term tendencies in EHD and shows events associated with human health impacts are increasing in frequency, intensity, and area affected. 

S.C. Pryor
Cornell University
Schoof, JT, TW Ford, and SC Pryor.  2017.  "Recent Changes in U.S. Regional Heat Wave Characteristics in Observations and Reanalyses."  Journal of Applied Meteorology and Climatology 56(9): 2621-2636.  https://doi.org/10.1175/jamc-d-16-0393.1.